Field
Aspects of the present disclosure generally relate to a power transmission apparatus that can execute wireless power transmission.
Description of the Related Art
In recent years, a wireless power transmission system has been known, which includes a power transmission apparatus that can transmit power in a contactless state without using a connector, and an electronic apparatus that can charge a battery attached thereto using the power transmitted from the power transmission apparatus. In the above-described wireless power transmission system, the power transmission apparatus that transmits power to an electronic apparatus by using an electro-magnetic resonance phenomenon has been known. In order to transmit power in a contactless state, the power transmission apparatus has to properly control power transmission by detecting a foreign object such as a metallic object or a near field communication (NFC) device that is not regarded as a power transmission target. Japanese Patent Application Laid-Open No. 2008-206231 discusses a method for detecting a foreign object placed on a power transmission apparatus based on load variation.
However, with the conventional method for detecting a foreign object based on the load variation caused by a foreign object, the foreign object may not be detected if the load variation caused by the inserted foreign object cannot be distinguished from the load variation occurring in a charging period or a load modulation communication period. Therefore, in a case where the foreign object cannot be detected, heat can be generated from the foreign object because of the magnetic field to exert an influence on the foreign object.